TY  - JOUR
A1  - Glaeser, Stefanie P.
A1  - Berghoff, Bork A.
A1  - Stratmann, Verena
A1  - Grossart, Hans-Peter
A1  - Glaeser, Jens
T1  - Contrasting effects of singlet oxygen and hydrogen peroxide on bacterial community composition in a humic lake
JF  - PLoS one
N2  - Light excitation of humic matter generates reactive oxygen species (ROS) in surface waters of aquatic ecosystems. Abundant ROS generated in humic matter rich lakes include singlet oxygen (O-1(2)) and hydrogen peroxide (H2O2). Because these ROS differ in half-life time and toxicity, we compared their effects on microbial activity (C-14-Leucine incorporation) and bacterial community composition (BCC) in surface waters of humic Lake Grosse Fuchskuhle (North-eastern Germany). For this purpose, experiments with water samples collected from the lake were conducted in July 2006, September 2008 and August 2009. Artificially increased O-1(2) and H2O2 concentrations inhibited microbial activity in water samples to a similar extent, but the effect of the respective ROS on BCC varied strongly. BCC analysis by 16S rRNA gene clone libraries and RT-PCR DGGE revealed ROS specific changes in relative abundance and activity of major bacterial groups and composition of dominating phylotypes. These changes were consistent in the three experiments performed in different years. The relative abundance of Polynucleobacter necessarius, Limnohabitans-related phylotypes (Betaproteobacteria), and Novosphingobium acidiphilum (Alphaproteobacteria) increased or was not affected by photo-sensitized O-1(2) exposure, but decreased after H2O2 exposure. The opposite pattern was found for Actinobacteria of the freshwater AcI-B cluster which were highly sensitive to O-1(2) but not to H2O2 exposure. Furthermore, group-specific RT-PCR DGGE analysis revealed that particle-attached P. necessarius and Limnohabitans-related phylotypes exhibit higher resistance to O-1(2) exposure compared to free-living populations. These results imply that O-1(2) acts as a factor in niche separation of closely affiliated Polynucleobacter and Limnohabitans-related phylotypes. Consequently, oxidative stress caused by photochemical ROS generation should be regarded as an environmental variable determining abundance, activity, and phylotype composition of environmentally relevant bacterial groups, in particular in illuminated and humic matter rich waters.
Y1  - 2014
U6  - https://doi.org/10.1371/journal.pone.0092518
SN  - 1932-6203
VL  - 9
IS  - 3
PB  - PLoS
CY  - San Fransisco
ER  - 
TY  - JOUR
A1  - Schellenberg, Johannes
A1  - Reichert, Jessica
A1  - Hardt, Martin
A1  - Klingelhöfer, Ines
A1  - Morlock, Gertrud
A1  - Schubert, Patrick
A1  - Bižić, Mina
A1  - Grossart, Hans-Peter
A1  - Kämpfer, Peter
A1  - Wilke, Thomas
A1  - Glaeser, Stefanie P.
T1  - The bacterial microbiome of the long-term aquarium cultured high-microbial abundance sponge Haliclona cnidata
BT  - sustained bioactivity despite community shifts under detrimental conditions
JF  - Frontiers in Marine Science
N2  - Marine sponges host highly diverse but specific bacterial communities that provide essential functions for the sponge holobiont, including antimicrobial defense. Here, we characterized the bacterial microbiome of the marine sponge Haliclona cnidata that has been in culture in an artificial marine aquarium system. We tested the hypotheses (1) that the long-term aquarium cultured sponge H. cnidata is tightly associated with a typical sponge bacterial microbiota and (2) that the symbiotic Bacteria sustain bioactivity under harmful environmental conditions to facilitate holobiont survival by preventing pathogen invasion. Microscopic and phylogenetic analyses of the bacterial microbiota revealed that H. cnidata represents a high microbial abundance (HMA) sponge with a temporally stable bacterial community that significantly shifts with changing aquarium conditions. A 4-week incubation experiment was performed in small closed aquarium systems with antibiotic and/or light exclusion treatments to reduce the total bacterial and photosynthetically active sponge-associated microbiota to a treatment-specific resilient community. While the holobiont was severely affected by the experimental treatment (i.e., bleaching of the sponge, reduced bacterial abundance, shifted bacterial community composition), the biological defense and bacterial community interactions (i.e., quorum sensing activity) remained intact. 16S rRNA gene amplicon sequencing revealed a resilient community of 105 bacterial taxa, which remained in the treated sponges. These 105 taxa accounted for a relative abundance of 72-83% of the bacterial sponge microbiota of non-treated sponge fragments that have been cultured under the same conditions. We conclude that a sponge-specific resilient community stays biologically active under harmful environmental conditions, facilitating the resilience of the holobiont. In H. cnidata, bacteria are located in bacteriocytes, which may have contributed to the observed phenomenon.
KW  - HMA sponge
KW  - bacterial symbionts
KW  - holobiont
KW  - antimicrobial defense
KW  - quorum sensing
KW  - bacteriocytes
Y1  - 2020
U6  - https://doi.org/10.3389/fmars.2020.00266
SN  - 2296-7745
VL  - 7
PB  - Frontiers Media
CY  - Lausanne
ER  -